1. Field of the Invention
The present invention relates to a mounting structure for an RFIC (Radio Frequency Integrated Circuit) chip included in, e.g., an RFIC device, such as a non-contact RFIC medium or a non-contact RFIC tag, which is used in an RFID (Radio Frequency Identification) system, for example.
2. Description of the Related Art
As an article management system, there is an RFID system for carrying out communication between an RFID tag and a reader/writer in a non-contact manner and transmitting information between the RFID tag and the reader/writer.
The RFID tag is made up of an RFIC chip in which ID information is written, and an antenna for transmitting and receiving an RF signal with respect to the RFID chip. As described in Japanese Unexamined Patent Application Publication No. 2010-009196, for example, the RFIC chip includes two input/output terminals and two dummy terminals, i.e., four terminals in total. A substrate for mounting the RFIC chip thereon also includes four mounting lands corresponding to the four terminals of the RFIC chip.
One example of an RFIC device disclosed in the above-cited Japanese Unexamined Patent Application Publication No. 2010-009196 is illustrated in FIG. 1. FIG. 1 is a sectional view of an RFIC device 10. A module component 20 including an RFIC chip 30 mounted in a recess 21 of a substrate 22 is bonded to a radiation plate 14 with a bonding material 16, e.g., an insulating adhesive sheet or adhesive, interposed therebetween. The radiation plate 14 is formed in a predetermined shape by using an electroconductive material.
The substrate 22 is made of a resin material. The recess 21 of the substrate 22 is formed by pressing the substrate 22. A wiring pattern 24 is formed not only on an upper surface 22a of the substrate 22, which is one principal surface thereof, but also along an inner peripheral surface 21t and a bottom surface 21s of the recess 21. A wiring pattern 26 is formed along a lower surface 22b of the substrate 22, which is the other principal surface thereof.
The RFIC chip 30 is mounted onto the wiring pattern formed along the bottom surface 21s of the recess 21 with a bump 12 interposed therebetween.
Input/output terminals and dummy terminals of the RFIC chip 30 are connected to the wiring pattern to which through-conductors 28 are connected.
Meanwhile, a thin and flexible mounting substrate, e.g., the so-called flexible substrate, has recently been often used as a substrate for mounting the RFIC chip thereon in order to reduce the size and thickness of the RFIC device. Because the flexible substrate is thin and flexible, it is highly adaptable for a thin-model RFIC device.
However, when stress is exerted on the mounting substrate causing, e.g., warping or bending of the RFIC device, there is a risk that the stress may be applied to the RFIC chip and the RFIC chip may be cracked or broken.